DESCRIPTION (provided by investigator The 1999-2001 National Health and Nutrition Examination Survey (NHANES) included a special investigation on body burdens and major predictors among U.S. adults of exposure to trihalomethanes (THMs), toxic and carcinogenic by-products of water disinfection. The NHANES blood measurements show evidence of widespread exposure in the population, with detection frequencies ranging from 79- 98 percent for individual THMs. This is a national public health concern since epidemiologic studies show associations between long-term exposure to treated water (through, for example, showering/bathing, . swimming, and consuming hot beverages made with tap water) and certain cancers (bladder, colorectal) as well as adverse birth outcomes (preterm delivery, small for gestational age/intrauterine growth restriction). Our long-term goal is to elucidate the factors predicting inter-individual variability in blood THM levels. Our specific aims are to use the NHANES 1999-2001 data to investigate the influence of pregnancy status on the relationship between water and blood THM levels among U.S. women, and to investigate the influence of intake of common inducers/inhibitors of CYP2E1, GSTT1, CYPD6 and other THM-metabolizing enzymes on blood THM levels in U.S. women and men. We will construct multiple linear regression models to evaluate these relationships, controlling for tap water THM concentrations. Results of the proposed investigations could help inform the development of recommendations on lowering THM body burdens among susceptible individuals. PUBLIC HEALTH RELEVANCE: The majority of Americans have detectable levels of trihalomethanes, toxic and carcinogenic by- products of water disinfection, in their blood. We will analyze data from the special trihalomethane investigation of the 1999-2001 U.S. National Health and Nutrition Examination Survey to investigate the influence of pregnancy status and the intake of common inducers/inhibitors of CYP2E1, GSTT1, CYPD6 and other xenobiotic metabolizing enzymes on blood trihalomethane levels. Results of the proposed investigations could help inform the development of recommendations on lowering THM body burdens among susceptible individuals.